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Health and genetics: beware of over-simplification

Diseases that are highly genetically determined are rare. Most diseases have multiple causes. The association of diseases with genes does not necessarily mean that the cause is genetic.

Nowadays, molecular genetics combined with epidemiological genetics make it possible to identify and characterise the molecular structure of a growing number of genes, some variants of which prove to be statistically associated with diseases.

The presence of damaged genes alone in a person is generally not enough to determine the manifestation of the signs and symptoms of a disease for certain. Other factors come into play, involving complex mechanisms about which much is still unknown. In short, the association of diseases with genes does not automatically mean that the cause is genetic.

In practice, diseases that are highly genetically determined are generally rare, or even very rare. The most common human diseases have multiple causes and are the result of complex interactions between genetic and other factors.

Most often, genes determine a heightened or lower vulnerability to various ailments in different people, and not an inescapable fate.

It is important not to lose sight of this notion in this era of increasingly commercialised genetic testing.

And above all we should not forget that it is a huge step from the identification of a gene associated with a disease to the prevention or treatment of that disease.

©Prescrire January 2010
 
"The role of genes in disease: beware of simplistic interpretations!" Prescrire Int 2009; 18 (104): 279-282 (pdf, subscribers only).
 
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